<div class="row">

    <div class="col-xs-3">
        买： <input type="number" class="form-control" placeholder="买" name="promotion_by" id="promotion_by" class="form-control promotion_by">
    </div>

    <div class="col-xs-4">
        送：<input type="number" class="form-control" placeholder="送" name="promotion_give" id="promotion_give" class="form-control promotion_give">
    </div>
</div>